Specific gravity apparatus

ABSTRACT

Apparatus useful in the determination of specific gravity of a test liquid by the falling-drop method is described. The apparatus provides an overflow feature wherein the test liquid which is dropped down a fluid column for specific gravity determination subsequently flows up a second column to a drain. This feature enables the initial fluid column to be conveniently repetitively used for specific gravity determinations.

United States Patent Clemens Jan. 30, 1973 [54] SPECIFIC GRAVITYAPPARATUS [75] lnventor: Anton Hubert Clemens, Elkhart, pmnary IndAssistant Examiner-Herbert Goldstein Attorney-Joseph C. Schwalbach,Louis E. Davidson, g y Laboratories, -9 Elkha", Harry T. Stephenson andGeorge R. Caruso ln 221 Filed: March 11,1971 I 1 ABSTRACT [2]] Appl.No.: 123,231 Apparatus useful in the determination of specific gravityof a test liquid by the falling-drop method is described. The apparatusprovides an overflow feature UISI a a a t a e 4 I t t a [5i] lnt. Cl.icolumn for Specific gravity determination [58] Field 0 Searc Sequenflyflows up a second coumn to a drain This 56 R C1 d feature enables theinitial fluid column to be con- 1 e erences veniently repetitively usedfor specific gravity deter- UNITED STATES PATENTS mmatlms- I 2,166,8427/1939 Kagan ..73/32 X 2 Claims, 1 Drawing Figure PATENTEDJAHSIO m5INVENTOR ANTON HUBERT CLEMENS ATTORNEY BACKGROUND AND PRIOR ART Thefalling-drop method is well known for determination of specific gravity.In this method a drop of the test liquid is allowed to freely fallthrough an immiscible fluid having a lower specific gravity. Two sensingmeans are located in aligned relation along the path of the fallingdrop. As the drop falls past each sensing means, it causes a signal tobe developed by each sensing means. The time differential between thetwo signals is a function of the difference in specific gravitiesbetween the falling drop and the surrounding fluid. This timedifferential can then be used to calculate the specific gravity of thedrop by well-known mathematical methods.

Most prior art apparatus used for thismethod employed a liquid dropfalling through a gaseous medium, such as air. Such apparatus has theadvantage that the falling drop can be easily discarded once it hasfallen past the two sensing means. It has the disadvantage that sincethere is a large difference between the specific gravities of mostliquids being tested and the surrounding gaseous medium, the velocity ofthe falling drop is relatively high. In order to prevent an inaccuratespecific gravity determination based on a slight error in the timedifferential measurement, the two sensing means can be spaced relativelyfar apart so that minor errors in time differential measurement are onlya small percentage of the actual overall time differential. This tendsto increase the overall size of the apparatus.

In an effort to overcome this problem and permit employment of smallerapparatus, it has been suggested to employ a test liquid drop fallingthrough another liquid, so that there is a relatively smaller differencein specific gravities between the test liquid drop and the surroundingfluid. The drop will thus fall at a relatively slower velocity. Thesensing means can therefore be closer together, since any minor errorsin measurement of time differential will not appreciably affect theoverall accuracy of time differential measurement. Such apparatus,however, presents a problem not thus far satisfactorily solved by priorart apparatus; i.e., that of separating the dropped test liquid from thesurrounding liquid for reuse of the apparatus. This is a particularlydifficult problem when the apparatus is to be used for repetitivemeasurement ofa large number of samples.

SUMMARY OF THE INVENTION In accordance with the present invention,apparatus is provided which is useful in the determination of specificgravity of a test liquid by the falling drop method which comprises agenerally U-shaped liquid receptacle providing first and second verticalcolumns, at least said first column containing a first liquid which issubstantially immiscible with and has a specific graviupper portion ofsaid second column at substantially the same rate as it is added to saidfirst column.

DESCRIPTION OF THE DRAWING The accompanying FIGURE is a verticalcross-sectional view of apparatus embodying the present invention.

DESCRIPTION OF THE INVENTION Referring to the accompanying FIGURE, theapparatus comprises a first liquid-tight container or chamber 10 formedby bottom wall 12, top wall 14 and sidewalls 16. The chamber 10 has anupper portion 11 and a lower portion 13. A first vertical conduit 18having an internal passage 20 is sealingly attachedat its lower end tothe top wall 14 and the internal passage 20 communicates with the upperportion 11 of the chamber 10. The upper end of the conduit 18 issealingly attached to and communicates with an opentopped reservoir 22formed by a bottom wall 24 and sidewalls 26 as shown.

Openings 30 and 32 are located in transversely opposing relation inconduit 18. Openings 34 and 36 are located intransversely opposingrelation in conduit 18 and are generally in longitudinal alignment withand below openings 30 and 32. Openings 30, 32, 34 and 36 are externallysealed by transparent members 38, 40, 42 and 44, respectively. Lightsources 46 and 48 having appropriate power supplies (not shown) aremounted against transparent members 38 and 42, respectively, so thatlight rays 50' and 52 from such light sources can pass through openings30 and 34 and subsequently through openings 32 and 36. Photosensitivedevices 54 and 56, such as photoconductors, having appropriate powersupplies (not shown) are mounted againsttransparent members 40'and 44,respectively, so that they can detect light passing through openings 32and 36. The photosensitive devices and-associated light rays form firstand second transverse sensing means which are capable of sensing anyobject that. interrupts or otherwise modifies the light rays, such as afalling drop. Sensors, other than photosensitive devices and associatedlight rays, can also be employed in apparatus of the present inventionif desired.

A second open-topped chamber 58 formed by bottom wall 60 and sidewalls62 is located above first chamber 10. a conduit 66 having an internalpassage'68 is sealingly attached to the bottom wall 60 with the passage68 communicating with the chamber 58. A second vertical conduit 70having an internal passage 72, an inlet end 74 and an outlet end 76-ismounted in liquid-tight'relation through a suitable aperture in top wall14 of chamber 10 and in liquid-tight relation through a suitableaperture in bottom wall 60 of chamber 58. As shown, the inlet 74communicates with the lower portion 13 of chamber 10 and the outlet 76communicates with chamber 58 at a point generally above the level ofopenings 30 and 32 in conduit 18.

A conduit 78'having an internal passage 80 and an outlet end 82 ismounted for disposition of the outlet 82 thereof through the open top ofand into the reservoir 22 in vertical alignment with passage 20 ofconduit 18. Passage 80 contains a sample of test liquid 94 and conduit78 is connected to suitable dispensing pumpmeans (not shown).

As shown in the FIGURE a generally U-shaped liquid receptacle isprovided by the reservoir22, conduit 18, chamber and conduit 70. Theoutlet end 76 of conduit 70 is located below the open top of reservoir22. This U-shaped receptacle is initially filled with a first liquid 84,such as a siliconefluid. The amount of liquid 84 introduced into thereservoir 22 initially must be sufficient to fill the chamber 10,conduit 70 and most of conduit 18. However, any additional liquid 84added thereafter will not result in raising the level of said liquid inthe conduit 18 above the level of the outlet 76 of conduit 70 since anysuch excess will simply overflow from the outlet 76.

In the preferred mode of operation of the apparatus of the presentinvention, successive portions of a second liquid 88, such as water,which has a specific gravity higher than that of said first liquid'84and which is immiscible with said vfirst liquid, are introduced toreservoir 22..Such second liquid will sink to the bottom of chamber 10.As the heavier second liquid 88 sinks to the lower portion 13 of chamber10, it displaces some of liquid 84 in chamber 10 causing a rise in theliquid levels in passages and 72. When passage 72 is originally filledwith liquid 84 to outlet 76, any rise in second liquid level in passage72 will cause liquid to overflow conduit 70 and drop into chamber 58 forsubsequent removal through the drain formed by passage 68. Any rise-intheliquid level in passage 20 can be accommodated by reservoir 22. Asportionsof second liquid 88 are added to chamber 10, the upper level 92of liquid 88 in chamber 10 will rise to a level just slightly aboveinlet 74 of conduit 70. Subsequent additions of portions of liquid 88will not increase the height of level 92, but the level of liquid 88 inpassage 72 will rise above level 92. Continued additions of liquid 88 tochamber 10 will cause liquid 88 to rise in passage 72 until itcompletely fills such passage. The first liquid in reservoir 22 willrise to form the first liquid level 86. The relationships betweenliquids 84 and 88 will then be as shown in the FIGURE. This apparatusconfiguration causes retention in the conduit 18 ofa predeterminedvolume of first liquid.

The above described apparatus thus has a second liquid 88 containedwithin conduit passage 72 and the lower portion 13 of chamber 10 to forma second vertical liquid column. This second liquid is immiscible withand has a higher specific gravity than the first liquid 84 which iscapable of floating on the second liquid 88 in chamber 10 and fillingthe upper portion 11 of chamber 10, passage 20 and reservoir 22 to forma first vertical liquid column.

In order to determine the specific gravity of a test liquid employingthe apparatus of the present invention, the conduit 78 containing testliquid 94, such as urine, which has a higher specific gravity than andis substantially immiscible with first liquid 84 but which is misciblewith second liquid 88, is placed in reservoir 22 in vertical alignmentwith passage 20. A pump (not shown) in communication with conduit 78 isactivated to discharge a specified amount of test liquid in the form ofdrop 96 from outlet 82 of conduit 78. Drop 96 falls past light rays 50and 52 'in'proximity to and action with the vertical liquid column. inconduit 18. and sending signals to'a computation circuit (not shown)tivating sensing means 54 and 56 mounted in conjuncfor determinationofspecific gravity. Drop 96 then falls into lower portion 13 of chamber10 which forms a collection means for such drop causing a displacementof a corresponding volume of liquid 88 out of the outlet 76 of conduitand subsequently out through the drain passage 68. This can be repeatedas many times as desired and the liquid levels will remain as shown inthe FIGURE. If similar test liquids are repeatedly used, liquid 88 willeventually be substantially the same composition as the test liquid andthe test liquid collected in chamber 10 will be subsequently conveyedout through the second vertical liquid column communicating withchamberlo for removal from the apparatus.

In another mode of operation of the apparatus the U- shaped liquidreceptacle formed by reservoir 22, conduit l8, chamber 10 and conduit 70is filled to outlet 76 witha first liquid 84, such as a silicone fluid.Successive drops of a test fluid 94, such as urine,-which has a higherspecific gravity than and issubstantially immiscible with said firstliquid 84 through passage 20 for measurement of specific gravity willform a second liquid in the lower portion 13 of chamber 10 causingdisplacementof a corresponding volume of liquid 84 out of the upper endof the conduit 72. continued addition of drops of test fluid throughpassage 20 with eventually result in passage 72 being filled with thetest fluid and the level of the first liquid 84 will rise in reservoir22 as shown in the FIGURE. In this operational mode, the test fluid 94acts in the same way as that described above for second liquid 88.

If a test liquid drop is allowed to fall onto liquid level 86, theresulting drop entering liquid 84 will tend to be misshapen in anon-predictable and non-reproducible fashion. This can tend to causeinaccuracies in the time differential measurement involving drop passagebetween light rays 50 and 52. The test liquid drop striking liquid level86 can also cause satellite smaller drops to be broken off the maindrop. These satellite drops cause noise in the sensing circuits andcreate inaccuracies in measurement.

With liquids 84 and 88 in equilibrium as shown in the FIGURE, thepreferred technique for introducing the test liquid drop is shown in theFIGURE. This technique eliminates the above-discussed disadvantages. Inthis technique conduit 78 is introduced into reservoir 22 by a mountingmeans (not shown) so that the outlet 82 of conduit 78 is below liquidlevel 86 of first liquid 84 and is in position 98 shown in dashed lines.The pump (not shown) communicating with conduit 78 is then activated todischarge the desired test liquid quantity. Conduit 78 is then withdrawnto the position shown by solid lines or is withdrawn completely fromreservoir 22. The inertia of the discharged test liquid portion preventsit from being withdrawn at the same rate as conduit 78 and it thusseparates from conduit 78 in the form of drop 96. This movement isreproducible and conveniently produces uniform shaped and sized dropswithout any satellite drops.

What is claimed is:

1: Apparatus for the determination of the specific gravity of a testliquid by the falling drop method which comprises a, generally U-shapedliquid receptacle providing first and second vertical columns whereinthe upper outlet of the second vertical column is at a level below theupper outlet of the first vertical column, at

least said first column containing a first liquid which is substantiallyimmiscible with and has a specific gravity less than that of said testliquid, means for introducing successive drops of said test liquid intosaid first liquid in the upper portion of said first column, means forsensing the travel of a falling drop of said test liquid through saidfirst liquid in said first column, the U- shaped configuration of saidreceptacle causing retention in said first column of a predeterminedvolume of said first liquid when successive drops of test liquid areintroduced into said first liquid in said first column and permittingsubsequent discharge of test liquid from the upper outlet of said secondcolumn at substantially the same rate as it is added to said firstcolumn.

2. Apparatus useful in the determination of specific gravity by thefalling drop method which comprises a first chamber having an upperportion and a lower portion, a reservoir located above said firstchamber, a first vertical conduit communicating between said reservoirand the upper portion of said first chamber, said first vertical conduithaving first and second transverse sensing means in conjunctiontherewith located in generally longitudinal alignment along said firstconduit, a second chamber having a drain communicating therewith locatedabove said first chamber, a second vertical conduit communicatingbetween the lower portion of said first chamber and said second chamberand having an inlet in said lower portion of said first chamber and anoutlet in said second chamber, .the outlet of said second verticalconduit being at a level below the reservoir for the first verticalconduit, the drain in said second chamber being located below the outletof said second conduit, and means for introducing a liquid drop intosaid reservoir in vertical alignment with said first vertical conduit,said second vertical conduit and said lower portion of said firstchamber being capable of containing a second liquid, said first verticalconduit, said reservoir and said upper portion of said first chamberbeing capable of containing a first liquid which is capable of floatingon said second liquid in said first chamber, said second liquid beingimmiscible with and having a higher specific gravity than said firstliquid, said apparatus being capable of functioning such that when adrop of test liquid having a specific gravity higher than that of saidfirst liquid is introduced into said reservoir and is allowed to dropthrough the first vertical conduit in proximity to said first and secondsensing means, said drop upon reaching the first chamber will displace acorresponding volume of said second liquid out of the outlet of saidsecond vertical conduit into said second chamber, such displaced liquidthen leaving said second chamber through said drain.

1. Apparatus for the determination of the specific gravity of a testliquid by the falling drop method which comprises a generally U-shapedliquid receptacle providing first and second vertical columns whereinthe upper outlet of the second vertical column is at a level below theupper outlet of the first vertical column, at least said first columncontaining a first liquid which is substantially immiscible with and hasa specific gravity less than that of said test liquid, means forintroducing successive drops of said test liquid into said first liquidin the upper portion of said first column, means for sensing the travelof a falling drop of said test liquid through said first liquid in saidfirst column, the U-shaped configuration of said receptacle causingretention in said first column of a predetermined volume of said firstliquid when successive drops of test liquid are introduced into saidfirst liquid in said first column and permitting subsequent discharge oftest liquid from the upper outlet of said second column at substantiallythe same rate as it is added to said first column.
 1. Apparatus for thedetermination of the specific gravity of a test liquid by the fallingdrop method which comprises a generally U-shaped liquid receptacleproviding first and second vertical columns wherein the upper outlet ofthe second vertical column is at a level below the upper outlet of thefirst vertical column, at least said first column containing a firstliquid which is substantially immiscible with and has a specific gravityless than that of said test liquid, means for introducing successivedrops of said test liquid into said first liquid in the upper portion ofsaid first column, means for sensing the travel of a falling drop ofsaid test liquid through said first liquid in said first column, theU-shaped configuration of said receptacle causing retention in saidfirst column of a predetermined volume of said first liquid whensuccessive drops of test liquid are introduced into said first liquid insaid first column and permitting subsequent discharge of test liquidfrom the upper outlet of said second column at substantially the samerate as it is added to said first column.